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SO2 amounts and yield calculation question

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Siwash

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I am coming across different total must yields that is complicating the SO2 amount I want to add to my crush in order to "clean the slate".

From experience and published evidence, finished yield is 2.5 gal/lug. But the gross (must) yield is trickier to calculate (you're dealing with liquid and solids with skins and juice). Some opinions put it at about 3.8 gal/lug.

Looking at last year's notes, I added 22 grams to 25 lugs (3.3 grams per 10 gallons based on MoreWine Guide to making red wine)

My notes state that I based this on a 66 galling yield from 25 lugs. But that's only 2.6 gal/lug so may have been too low. I think it should have been closer to 30 grams based on a 3.5 gal yield/lug It did ferment well...

Where are you guys at with this? About to crush this morning so I would appreciate some help. Thoughts? Thanks!
 

Stressbaby

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Basically it sounds as if you are asking if the SO2 addition is based on the total must volume or the final yield volume. I generally use the latter. The Morewine guide's TA calculations focus on the juice volume, not the volume of the entire must. So I have always assumed that SO2 dosing went the same way. So it sounds to this newbie that you had it right last year. Now let's see what more experience people have to say.
 

Siwash

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For SO2 management (post fermentation) I think one is working with net and not gross yields. But I am referring to the initial addition of So2 when one is attempting to kill off native yeast just prior to pitching commercial yeast.
 

sct1984

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Since I have not actually made wine from grapes, perhaps my opinion is worth very little...

But I do have a question - maybe I am missing something, but are you adding SO2 directly to the grapes pre-crush? Is there a reason not to measure the actual volume of must, as opposed to trying to calculate it and add pre-crush? It just seems that there could be so many variables that would affect the over all yield of must, and then again so many variables that would affect the yield of juice.
 

ibglowin

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Just get the volume of whatever shape your Primary is. If your using a Brute, its a cylinder. Take your measurements and calculate your must volume straight off that.

That is a real world number and not an estimate based on what? Grape Varietal? That is completely worthless IMHO.

Where are you guys at with this? About to crush this morning so I would appreciate some help. Thoughts? Thanks!
 

heatherd

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@Siwash I agree with Mike that you should calculate the total volume of the must and dose based on that.
 
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